,after a very short power cut ,i presume

What am i doing wrong ?

 

Could be a scheduled program set to turn the computer on.

Click start>program>accessories>system tools>disk defragmenter

In there check it's schedule is switched off or at least designed to run during the day.

A power cut might do it as well, my computer on the rare occasion will do this.

 

Go into Bios,

there will be a setting that says something like.. "on / after power interruption.. wake / sleep state"

or its "resume after power interruption y/n"

Mart

 

Ghosts?

 

It was maybe in hibernate mode and woke itself up?

 

Windows Vista automatic updates has been known to have the power to wake a machine to attempt to download anything it needs. Head off into Start>Control Panel>Windows Update>Change Settings>choose an appropriate time for it to make the attempt (like during the day when your awake )

 

that would freak me out

 

I wouldn't worry until it starts to ask if you would like a nice game of chess

 

I had it happen once when the Power supply was on it's way out.
Had random starting of the PC for about a week, then one day "poof".

After opening the PC I found the power supply to be the culprit.
Lots of components were brownish, including the ones leading to the ATX plug that goes on the motherboard.

 

Or emptying your bank account through online banking
And then sending you taunting emails

 

Mine does it regularly - updates and virus scans.

 

This is usually caused by the BIOS features.....

Either the "Power on" settings or "wake on LAN".